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Thursday, October 31, 2013

It’s been a while since I read Marc Kuchner’s book “Marketing for Scientists”. I hated the book as I’ve rarely hated a book. I did not write a review then because it was a gift from an, undoubtedly well-meaning, friend who reads my blog. As time passed though, I changed my mind. Let me explain.

Product advertising and marketing is the oil on the gears of our economies. Its original purpose is to inform the customers about products and help them to decide whether they fit their needs. But marketing today isn’t only about selling a product, it’s also about selling a self-image. What we decide to spend money on tells others what we consider important and which groups we identify with.

In the quest to attract customers, advertisements often don’t contain a lot of information, and sometimes they bluntly lie. And so we have laws protecting us from these lies, though their efficiency differs greatly from one country to the next as Microsoft learned the hard way.

Everybody knows adverts make a product appear better than it is in reality, that microwave dinners never look like they do on the images, lotions won’t remove these eye bags, and ergonomic underwear will not make you run any faster. The point is not that advertisements bend reality but as that advertisements work regardless, just by drawing attention and by leaving brand names in our heads – names that we’ll recognize later. The more money a company can invest into good advertisement, the more likely they are to sell.

It isn’t so surprising that capitalistic thought is increasingly applied not only to the economy but also to academic research. Today, tax-funded scientists, far from being able to dig into the wonders of nature unbiased and led by nothing but their interests, are required to formulate 5 year plans and demonstrate a quantifiable impact of their work. And so scientists are now also expected to market themselves, their research and their institution.

Scientific knowledge however isn’t a product like a candy bar. A candy bar isn’t right or wrong, it’s right for you or wrong for you, and whether it’s right or wrong for you depends as much on you as on the candy bar. But the whole scientific process works towards the end of objective judgment, towards finding out whether a research finding should be kept or tossed. Scientific knowledge is eventually either right or wrong and academic research should be organized to make this judgment as efficiently as possible.

Marketing science is not helpful to this end for several reasons:

It puts at advantage those who are either skilled at marketing or who can afford help. This doesn’t necessarily say anything about the quality of their research. It’s not a useful selection criterion if what you are looking for is good science. Those who shout the loudest don’t necessarily sell the best fish.

Marketing of science advertises the product (research results), while what people actually want to sell is the process (the scientist’s ability to do good research). It draws attention towards the wrong criteria.

It has a positive feedback loop that gradually worsens the problem. The more people advertise their work, the more others will feel the need to also advertise their work as well. This leads, as with advertisement of goods, to a decrease of objectivity and honesty until it eventually nears blunt lies.

It takes time away from research, thus reducing efficiency.

In quantum gravity phenomenology, you will frequently see claims that something has been derived when in fact it wasn’t derived, or that something is a result, when in fact it is an ad-hoc assumption. I am aware of course, such exaggerations are advertisements, made to convince the reader of the relevance of a research study. But they’re not helpful to the process of science and even worse for science communication.

That’s why I hated Kuchner’s book. Not because his marketing advice is bad advice, but because he didn’t consider the consequences. If all researchers had Marc Kuchner’s “sell yourself” attitude, we’d end up with a community full of good advertisers, not full of good scientists. It’s the inverse of the collective action problem: A situation in which we would all benefit from not doing something (advertising), but each individual would put themselves at a disadvantage when behaving differently (not advertising), and so we all continue to do it.

Here’s why I changed my mind.

Researchers market and advertise because they have to, owing to the very real pressure of the collective action problem. There are too many people and not enough funding. Marketing might not be a good factor to select for, but standing out for whatever reason puts you at an advantage. The more people know your name, the more likely they’ll read your paper or your CV, and that’s not a sufficient, but certainly a necessary condition for survival in academia. And then there’s people, like Kuchner, who make money with that survival pressure. Sad but true.

Yes, this is a bad development, but collective action problems are thorny. Complaining about it, I’ve come to conclude, will not solve the problem. But what we can do is work towards balance. What we need then is the equivalent of customer reviews and independent product tests – what we need is a culture that encourages feedback and criticism.

Unfortunately presently feedback and criticism on other people’s work is not appreciated by the community. Criticism is typically voiced only on very popular topics, when even criticism on other’s work is advertisement of one’s own knowledge, think climate change, arsenic life, string theory. But it’s a very small fraction of researchers who spend time on this, and it’s only on a small fraction of topics. It’s insufficient.

“In recent years, authors and readers have been able to post online comments about Nature papers on our site. Few bother. At the Public Library of Science, where the commenting system is more successful, only 10% of papers have comments, and most of those have only one.”

This really isn’t surprising. Few bother because in terms of career development it’s a waste of time.

In contrast to the futile attempt of preventing researchers from advertising themselves and their work however, the balance can be improved by appreciating the work of those who provide constructive criticism. By noting the community benefit that comes from researchers who publicly comment on other’s publications, by inviting scientists to speak not only for their own original work, but for their criticism of other people’s work, and by not thinking of somebody as negative who points out flaws. Because that consumer feedback is the oil on the gears that we need to keep science running.

Tuesday, October 29, 2013

It’s not like nothing happened, I just haven’t had the time to keep you updated on our four-body problems.

Earlier this year, we had handed over the stalled case on our child benefits to an EU institution called “SOLVIT” that takes on problems with national institutions under EU regulations. Amazingly, they indeed solved our problem efficiently and quickly. And so, after more than two and a half years and an inch of paperwork, Stefan finally gets child benefits. Yoo-hoo! If you have any institutional problem with a family distributed over several EU countries, I can recommend you check out the SOLVIT website. I really wish though the Germans and the Swedes could converge on one paper punch pattern, then I wouldn’t have to keep two different types of folders.

She knows the numbers from
1 to 10, but not their order.

Lara and Gloria will turn 3 in December and so we are about to switch from daycare to Kindergarten. They both speak more or less in full sentences now and come up with questions like "Where do clouds go at night?" and "Mommy, are you wearing underwear?" They still refer to themselves by first name though rather than using “I”, and are struggling with German grammar. At daycare the kids sing a lot, which feeds them weird vocabulary that may be delivered spontaneously in unexpected situations, Butzemann! Tschingderassabum! Wo ist meine Zie-har-mo-ni-ka? The girls both love puzzles and Lego and the wooden railway. On occasion they now demand to sit on their potty, though the timing isn’t quite working yet.

Lara can't let go of the binky, but isokay as long as it's in the vicinity.

I meanwhile have decided, after a long back and forth, that I’ll not attend next year’s FQXi conference. The primary reason is that I looked up the flight connections and the inconvenience of getting to Vieques Island exceeds my pain tolerance. I am very reluctant these days to attend any meeting that requires me to be away on weekends and that isn’t located in vicinity of a major international airport, thus adding to my travel time. Secondary reason is that I’m not particularly interested in the topic ("The Physics of Information"), and I can just see it degenerating into yet another black hole firewall discussion. At the same time
I’m sorry to miss the meeting, because from all the conferences that I’ve attended the FQXi conferences were undoubtedly the most inspiring ones.

Speaking of pain tolerance, I ran a marathon last weekend. I’ve always wondered why people run marathons. Now that I have a finisher medal, I am still wondering why people do this to themselves. I really like running, but there were too many people and too much noise on these 42 km for me.

I admit I plainly didn’t know before my first 10k about a year ago that these races tend to have typically only 20% or so of female participants. (The Frankfurt marathon had 15%, though the recent numbers from the USA look better). I find this surprising given that most of the people I meet jogging in the fields tend to be women. Neither did I know until some months ago that women weren’t even allowed in marathons until the mid 1970s, for somewhat mysterious reasons that seem to go back to the (unpublished) beliefs of some (unnamed) physicians that the female body isn’t meant for long-distance running – a claim that nobody bothered to check until some women stood up and disproved it. It’s an interesting tale, about which you can read here.

Friday, October 25, 2013

The girls were about a year old and I was working from home. As I was reading yet another referee report that came with the preamble “we regret to inform you...,” I watched Gloria trying to push a square block through a round hole. We were really trying the same thing, I thought.

Decoding metaphors and using analogies is a prototypical right-brain task, a pattern finding that helps us get a grip on new situations quickly and that sheds new light on the familiar. Metaphors and analogies are omnipresent in literature and the arts, in humor and also in education. And popular science writing is full of it.

But relying on metaphors is like traveling to a new country and then heading to Starbucks. The very reason to do it is also what limits the experience. It’s familiar and easy to understand, but it prevents us from learning something new. This is why I have a love-hate relationship with Starbucks and other metaphors.

Love: Analogies and metaphors build on existing knowledge and thus help us to understand something quickly and intuitively.

Hate: This intuition is eventually always misleading. If a metaphor were exact, it wouldn’t be a metaphor.

And while in writing, art, and humor most of us are easily able to tell when an analogy ceases to work, in science it isn’t always so obvious.

When it comes to physics I can most often tell when an analogy fails to capture the actual science. But in other areas of science this sometimes is not clear to me. There are for example these artistic images that frequently accompany popular science accounts of new drugs or cancer treatments. You know, the ones with the molecules that fit like keys into locks of other molecules, or that cut through molecular bonds. I am reasonably sure that these explanations suggest a clarity of the underlying mechanism and structure that most often doesn’t quite exist in the actual data. But how much of it is science and how much of it is art is difficult for me to tell.

“[I]n the late 1990s, computer scientists, physicists and engineers were fuelled by the idea that they might be able to direct cells in the same way that people program computers. In the laboratory, researchers started to use computing and engineering metaphors –switches, oscillators and logic gates, for instance – both to guide the design of synthetic constructs and to understand how natural systems function. Almost immediately, scientists were confronted with the uncertainties and constraints of engineering in the cellular context. Engineering concepts and metaphors could serve only as an inspiration...

Scientists using metaphors among themselves are often aware of, and even careful to point out, the subtleties that could be misconstrued. Problems tend to arise when metaphors are used outside the laboratory...

Faced with explaining the messy complexity and uncertainty of science to the public, it is understandable that scientists reach for metaphors. But [this] sends a message to policy-makers and laypeople that scientists can already make biological systems that are reliable and controllable. It widens rather than closes the gap between scientific realities and the expectations of policy-makers and the public.”

The same problem exists in physics, though at least in the area I work in there aren’t all that many implications for public policy. But I’ve seen it over and over again that people take analogies too seriously and start trying to build arguments on them. Suddenly a rubber sheet isn’t just an analogy for space-time, but it is space-time. The universe is an inflating balloon, the Higgs particle is a rumor, and entangled particles are shoes in parcels.

Except that, well, they’re not. The universe isn’t a clockwork and it’s not a drum either; the brain isn’t a computer, black holes are not cannibals and indeed not even black.

The main reason we use mathematics for scientific theories is that it’s a particularly clean way of thinking, uncluttered from what the right brain wants to associate. An electron isn’t a spinning top, it’s an element of a Hilbert space that transforms under the spinor representation of the Lorentz-group. There is really no metaphor that’ll do equally well. Feynman diagrams seem to be particularly prone to misinterpretation as many people believe they depict physical particles, while they are actually a handy short-notation for lengthy integrals.

But my uneasiness with metaphors and imagery goes beyond the communication issue.

If you spend some time with a set of equations, pushing them back and forth, you’ll come to understand how the mathematical relationships play together. But they’re not like anything. They are what they are and have to be understood on their own terms*.

Thus, as much as I value metaphors for the intuition that can serve as a guide to new ideas, I also mistrust them. We learn much more from the failure of metaphors than from their success.

I admired Gloria for her persistence in trying to push the square block through the round hole. Then Lara took the piece out of Gloria’s hand, opened the lid of the bucket and put the block in. Problem solved. If only it were so easy with my papers…
*That is unless you are onto a theory that is truly equivalent (‘dual’) to some other theory.

Monday, October 21, 2013

One of the most general expectations of quantum gravity is that space-time is not the smooth background of General Relativity, but instead a wildly fluctuating, bubbly, foamy mess. Seeing the quantum properties of space-time directly is not presently possible, but what we can see is whether the quantum gravitational behavior affects the way particles travel through space-time.

One way this could happen is by distorting paths so that photons of different frequency (energy) move at slightly different speeds. Such an effect is referred to as ‘dispersion’. Next to dispersion there is dissipation, which is basically energy loss into the background. While quantum gravitationally induced dispersion has received substantial attention during the last decade, dissipation hasn’t received as much love.

In a nice and straight-forward recent paper dissipation finally got some love from Liberati and Maccione

They start with a general hydrodynamic ansatz that assigns space-time the properties of a fluid, notably a viscosity, which causes dissipation. The microscopic theory that would give rise to such a hydrodynamic behavior they leave unspecified and just ask what observable consequences a non-vanishing space-time viscosity would have. With this ansatz, they make an expansion of the dispersion relation and collect the dissipative (imaginary) contributions.

Then they look at observations of highly energetic photons from a distant source, the Crab nebula. If space-time was viscous, the photons would lose energy during their travel. Already the rather conservative estimate that the photons of the highest observed energies shouldn’t have lost more energy than they have left at arrival leads to very tight constraints. If the photons lose energy faster than that, the spectrum we receive on Earth would be highly distorted and pretty much incompatible with our knowledge of astrophysics.

This constraint from existing data clearly rules out Planck scale effects, ie effects that plausibly have a quantum gravitational origin, at first order. Better constraints can be obtained by drawing upon concrete astrophysical models for the typical energy of photons that are emitted, so it seems likely that in the future we will see even better constraints on this.

Much like with violations of Lorentz-invariance this is a case where nothing has been found. Yeah, Einstein was right, again. But this doesn’t mean that nothing has been learned. We’ve learned that any model for an emergent space-time that does not have a very small, almost vanishing, viscosity is clearly incompatible with observation.

Thursday, October 17, 2013

The IOP's member magazine "Physics World" turns 25 and has an anniversary issue out. It's full of interesting articles, some more information about the content is on the Physics World Blog, and you can download the issue for free here. It contains a contribution from me on one of the "five biggest unanswered questions in physics" -- "Can we unify quantum mechanics and gravity?"

For the download you apparently have to agree to end up on a newsletter email list. If you don't want that but would like to read my piece, send a brief note to hossi at nordita dot org.

I don’t normally have a lot to do with quantum foundations, especially not since I left Perimeter Institute. And so I learned many new things and got feedback on my paper. It was a useful meeting for me – but it was also a little strange.

Most of the feedback I got was people telling me they don’t believe in superdeterminism, wanting to know why I believe in it, not that I’m sure I do. Discussions turned towards final causes and theology. I’m a phenomenologist, I heard myself saying, I couldn’t care less what other people believe, I want to know how it can be tested. Faintly, I heard an echo of a conversation I had with Joao Magueijo at PI some years ago. Boy, I thought back then, does this guy get explosive when asked about his beliefs. Now I think he must have been spending too much time with the quantum foundations folks. Suddenly I’m very sympathetic to Joao’s attitude.

Quantum foundations polarizes like no other area in physics. On the one hand there are those actively participating who think it’s the most important thing ever but no two of them can agree on anything. And then there’s the rest who thinks it’s just a giant waste of time. In contrast, most people tend to agree that quantum gravity is worthwhile, though they may differ in their assessment of how relevant it is. And while there are subgroups in quantum gravity, there’s a lot of coherence in these groups (even among them, though they don’t like to hear that).

As somebody who primarily works in quantum gravity, I admit that I’m jealous of the quantum foundations people. Because they got data. It is plainly amazing for me to see just how much technological progress during the last decade has contributed to our improved understanding of quantum systems. May that be tests of Bell’s theorem with entangled pairs separated by hundreds of kilometers, massive quantum oscillators, molecule interferometry, tests of the superposition principle, weak measurements, using single atoms as a double slit, quantum error correction, or the tracking of decoherence, to only mention what popped into my head first. When I was a student, none of that was possible. This enables us to test quantum theory now much more precisely and in more circumstances than ever before.

This technological progress may not have ignited the interest in the foundations of quantum mechanics but it has certainly contributed to the field drawing more attention and thus drawing more people. That however doesn’t seem to have decreased the polarization of opinions, but rather increased it. The more attention research on quantum foundations gets, the more criticism it draws.

“Shut up and let me think” is the title of an essay by Pablo Echenique-Robba which you can find on the arxiv at 1308.5619 [quant-ph]. In his personal account Pablo addresses common arguments for why research on quantum foundations is a waste of time. I’ve encountered most of these and I largely agree with his objections. But let me add some points Pablo didn’t mention.

I do have my issues with much of what I’ve seen in quantum foundations. To begin with, most of it seems to be focused on non-relativistic quantum mechanics. That’s like trying to improve the traffic in NYC by breeding better horses. If you can’t make it Lorentz-invariant and second quantized I don’t know why I should think about it. More important, I can’t fathom what most of the interpretation-pokers are aiming at. It’s all well and fine with me to try to find another formulation for the theoretical basis of quantum theory. But in the end I want to see either exactly what the observable differences are or I want to see a proof of equivalence. Alas, there seems to be a lot of talk about, well, interpretations which do neither one nor the other. Again the phenomenologist lacks the motivation to think about it.

Despite these reservations I think that research on the foundations of quantum mechanics is of value, again for a reason that Pablo did not address in his paper, so I want to add.

I’ve been educated in the “shut up and calculate” philosophy with my profs preaching Feynman’s mantra that nobody understands quantum mechanics, so don’t bother trying. Needless to say I, as probably most students, was not so much deterred as encouraged by this, so we dug a little into the literature. If you dig, it gets into philosophy very quickly. That’s not necessarily a bad thing, but most students come around to realize they wanted to study physics, not philosophy, and they move on to calculate. I’m among those who feel comfortable with a mathematical framework that “just” delivers results and that can be used to describe nature. To me science is “just” about making good models.

But those who are criticizing research on the foundations of quantum mechanics on the ground that everything has been understood are dismissing a way to arrive at an improved description of nature, and they are dismissing it based on unjustified arrogance about their superior motives.

Science progresses by evaluating the use of models about nature in the form of specific hypotheses. What we call ‘scientific method’ are procedures that have proved efficient in creating good hypotheses and tests thereof. Not only do these methods change (hopefully improve) over time, what constitutes a ‘good’ hypothesis also depends on beliefs and social dynamics. In the end what matters is not how somebody arrived at a hypothesis, but whether it works. That’s the essence of scientific progress.

The action principle, gauge-symmetry, and unification, for example, have proved dramatically useful in the construction of theories. And that they have been useful in the past is a good reason to employ them in the future search for improved theories. The same goes for naturalness. A theory that isn’t ‘natural’ is typically believed to be incomplete and in need of improvement or at least additional explanation. Yet all that says is that it’s a criterion which researchers draw upon to arrive at better theories. There’s no proof that this will work. It’s a reasonable guess, that’s all. How reasonable depends on your attitude, your beliefs and on whether you think it’ll land you a job.

And so some may guess there is something to be gained by poking around on the foundations of quantum mechanics. You might not believe that the reasons for their interest are good reasons, much like I don’t believe in naturalness and others don’t believe in a theory of everything. But in the end it doesn’t matter. In the end what matters is not what motivated people to study some research question, but only whether it led to something.

My support for quantum foundations thus comes from a live-and-let-live attitude. Maybe studying the foundations of quantum theory will improve our understanding of the fundamental nature of reality. Maybe it won’t. I don’t understand most of their motivations. But then they don’t understand mine either.

Those who are dismissing quantum foundations as a waste of time I want to ask to consider the consequences of this research in fact revealing a different theory underlying quantum mechanics, one that allows us to manipulate quantum processes in novel ways. The potential is enormous. It’s not a stone that should be left unturned.

Friday, October 11, 2013

It’s a grey and foggy Friday here. The clouds are hanging around like they’ve been out all night and even the leaves are too tired to jump off the trees. A cold is knocking on the door, or at least my brain is mush and I could need an excuse for that. There’s two guys in front of my window tearing off the balcony. If they don’t drink beer and watch me, they make noise and I’m rather unsuccessful in trying to ignore them. In summary, I’m pretty dysfunctional and in a pissy mood. You don’t want me to write a referee report on your paper in this condition.

To cheer me up, I decided I’ll go and disagree with Sean Carroll on something, just for the fun of it.
Sean had a recent Op Ed piece in the NYT arguing that “in the future the [Nobel] prize committee should be allowed to consider institutions and collaborations as well as individuals.” It’s well written and worth a read, so have a look. I’ll grab a coffee and wait till you’re back.

There are three ways to approach the question whether the criteria for the Nobel Prize should be changed. One is to look at Alfred Nobel’s original will. He explicitly stated that the prizes be given to “persons”. But then it’s been a while. Second, one can try to guess whether Nobel would have wanted the criteria to be altered if he would be alive today. For me that’s too much psychology and I’ll leave that to somebody else. Third, we can ask whether it would be beneficial for science or for the communication of science and that seems to me the most fruitful approach.

Sean basically argues that science is a community enterprise and if one honors certain discoveries then credit should be given to everybody involved. Scientists take acknowledgement of contributions very, very seriously because it’s essentially what they live from. That’s the reason for long author lists. These lists keep getting longer as the topics we work on become more involved and the experiments become more complex.

However, science has always been a community enterprise. Every single discovery that has been made became possible only through the work of many others before and alongside those who put the pieces of the puzzle together.

Researchers who study the network dynamics of science refer to breakthrough events as ‘pivot points’. They’re combinations of existing knowledge that solve a problem and create a new basis for future research, not seldom founding entirely new fields. You might be interested to have a look at this paper that visualizes pivot points in citation networks with superstring theory as one example.

It has happened frequently in the history of science that major discoveries were made almost simultaneously by several people. That’s not a coincidence but due to the nature of breakthrough discoveries. They typically combine existing knowledge in just the right way. Having the right knowledge at the right time and seeing the potential of this combination is what makes a genius. And that’s what the Nobel Prize honors.

The Nobel Prize, in my opinion, cannot give credits to everybody involved in a discovery because that’s futile. It should then focus on those on whose work was the basis of a new understanding of nature. It is a prize for persons and individual contributions. There are many scientific societies and foundations who give out prizes and awards and nobody ever complains that somebody gets such a prize when there’ve been many other people working on the same thing. That’s because it is understood that these awards are for persons and their dedication and foresight in the first place, and for the specific topic in the second place.

I don’t know anybody who went into science or pursued their research with the aim of winning a Nobel Prize. It is generally recognized that hard work and intelligence is necessary but not sufficient, and that it also takes a good dose of luck which is beyond our influence. So the Nobel Prize doesn’t actually serve as an incentive, or at least not much so. But the mere fact that the Nobel Prize is awarded to (a few) individuals documents the value of personal sacrifice. Giving such an honor to institutions is akin to doing away with private property in communism and believing that everybody cares for the well-being of the group as they do for their own. It doesn’t work because most people want to be recognized as individuals, not as members of collectives. That’s true also for scientists.

There is another reason why giving the Nobel Prize to collaborations or institutions is not a good idea. Nobel Prize winners like no other scientists become spokespeople for their field of research – and beyond. They are being heard. Nobel Prize winners play an important role in representing the interests of the scientific community. Granted, not all of them might live up to expectations, but I think that most of them are aware of the influence they suddenly acquire. Giving the prize to institutions would throw away this voice that scientists have to speak for them, and they don’t have many of these voices.

So I think the Nobel Prize committee is doing the right thing in giving the prize to persons. Because scientists want to be recognized as people, not as members of a collective.

It has started to rain and the balcony guys have packed their tools and left me with a semi-deconstructed balcony and empty beer bottles. Time to finally write these referee reports; keep the gear-wheels of the system turning.

Wednesday, October 09, 2013

Gravity waves. They are pretty but have
nothing to do with gravitational waves. Image Source: UWO.

Krauss and Wilczek recently posted a brief note on the arXiv. They present a dimensional argument that claims signatures of relic gravitational waves in the cosmic microwave background (CMB) would be evidence for quantum gravity.

Relic gravitational waves are perturbations of space-time created at the Big Bang. They cannot presently be directly detected, but if they exist they would affect the polarization of CMB photons. The Planck satellite mission is about to deliver data on CMB polarization, so Krauss and Wilczek’s is a very timely contribution.

While their dimensional argument is original and compelling in its simplicity, what they say is not particularly surprising and known to researchers familiar with the subject. The argument means essentially if there are no suitable matter sources that could cause space-time perturbations, then the only way relic gravitational waves can have been created is through quantum effects. That’s because it needs a mass scale to get the dimensions right and Newton’s constant will only give a mass-scale when suitably combined with Planck’s constant, thus indicating a quantum effect.

The argument however only works without matter that brings in anisotropic stress. It would still work if the matter was solely scalar fields because these don’t contribute to the anisotropic stress, but electromagnetic radiation could deliver such a contribution. Be that as it may, this means by a purely dimensional argument alone it is hard if not impossible to reverse the logical arrow, that being the question whether relic gravitational waves could have been created in a non-quantum fashion.

Few few people doubt that relic gravitational waves exist and are quantized. It would certainly be exciting to have evidence that this treatment of the early universe is correct, but it must be said that this is not evidence for what the community commonly refers to as quantum gravity.

“Quantum gravity” is normally meant to be the fundamental theory for the quantum nature of space and time. The quantization that is being used for gravity in the early universe is normally explicitly referred to as “perturbatively quantized gravity”. It is expected by all but a few dissidents that perturbatively quantized gravity is the correct effective limit of any theory of quantum gravity. The mere existence of such quantized perturbations thus tells us little. More telling is the spectrum of the perturbations which depends on what happened in the early universe, for example on whether there was a Big Bang or a Big Bounce, and that does indeed depend on the full theory of quantum gravity.

Evidence for relic gravitational waves would give strong support to the validity of perturbatively quantized gravitational waves (essentially quantum field theory in curved background), but it takes more than a dimensional argument to show that other models cannot produce the same observation. And even if that could be shown, the mere existence of the gravitational wave background does not teach us much about the non-perturbative theory of quantum gravity. Thus, Krauss and Wilczek’s argument makes a good point but its relevance for research in quantum gravity is limited.

Kudos to Jakub Mielczarek for helpful communication.

Bonus: Krauss at a recent discussion following his public lecture in Stockholm. Spot the American among the Swedes :p

Saturday, October 05, 2013

Thank you, you can stop sending me the link to the NYT article “Why Are There Still So Few Women in Science?” I assure you I saw it. It just didn’t seem to say anything we didn’t know already, so I wasn’t about to mention it. Alas, it seems to have triggered another wave of public commiseration about the alleged lack of women in the sciences, and it seems moreover I’m expected to have an opinion, so here you go.

I have a hard time believing this bemoaning of the current state of affairs is sincere. If Americans would take the issue seriously they’d have paid maternity leave to assure employers don’t think twice hiring women in their fertile years who haven’t yet reproduced. If you want more women in science, that’s where you should start, not with complaints about dress code schizophrenia. Everybody with half a brain knows that a pregnant or nursing woman will not be as productive as her testosterone fueled colleague. That’s not a bias, that’s capitalism.

Please don’t hold it against me that I published several papers during my parental leave – these were written much earlier and just submitted while I was learning how to ten-finger type with a baby or two hanging on my nipples.

Paid maternity leave and paid parental leave might not be sufficient, but necessary, hear me. And it’s not only the women who will benefit from this, but it’ll generally level the playing field for those who want to have children before the age of 40.

Having said that, I’m always uncomfortable to address the question of women in science, physics in particular. I’m not “women in physics”, I’m one woman in physics, and I don’t want to speak for others who have made experiences very different from mine. I don’t doubt that many women feel awkward in male-dominated environments or that they don’t like to stand out by wearing ‘feminine’ clothes or that they think it inappropriate if they get hit on by a colleague. But Eileen Pollack, who wrote the recent NYT piece, is similarly one woman in physics, so let me to add my own experience to the points she brings up just for balance.

I’ve never been a girly girl; quite possibly having three brothers played a role in that. My teachers constantly complained that I was too quiet, not social enough, did not speak up often enough, did not play with the other kids and was generally awkward around people. I spent a lot of time with books. I never had problems at school, unless you count that I was about as unsporty as you can be. As a teenager I was very into science fiction. And since I wanted to tell the science from the fiction, I piled up popular science books alongside this. You can extrapolate from here.

I studied math and physics primarily because I don’t understand people. People are complicated. They don’t make sense to me and I don’t know what to do with them. Which is probably why I don’t spend a lot of time thinking about whether or not my male colleagues behave appropriately. They don’t make sense either way. And the women, they make even less sense. Take in contrast a problem like black hole information loss or the recent firewall controversy. Clean, neat, intriguing. So much easier.

Yes, there’ve been some guys who’ve tried to pick me up on conferences but for what I understand of human mating rituals it’s the natural thing to happen among adults and I just say no thanks (the yes-thanks days are over, sorry). Indeed, there’ve been sexist jokes and I try to stay away from people who make them because such jokes come from brains preoccupied with differences between the male and female anatomy rather than the actual subject matter of the discussion. There have been the elderly guys who called me “little girl” and others who pat my shoulders. And yes, that’s probably the reason why I’m sometimes acting more aggressive than I actually am and why my voice drops by an octave when I’m trying to be heard by my male colleagues.

But by and large the men I work with are decent and nice guys and I get along with them just fine. Most of the time I’m not consciously taking note of them having a crinkly chromosome I don’t have, and my subconsciousness was not consulted for this blogpost. Yes they interrupt me when I speak and it’s annoying, but they interrupt each other as well, and I’ll admit that I too have developed the unfortunate habit of cutting off others, patience has never been my strong side. I still paint my toenails pink and I do have baby pictures in my office.

I’ve seen a bunch of do and don’t-do lists for men in academia when talking to their female colleagues. If you’d give me a set of do and don’t-do’s for how to deal with my male colleagues, I would decide it’s too complicated and just avoid talking to them all together. So I don’t think these lists are very helpful. I understand that everybody has their touchy points and they want others to respect them, but society has never worked by people giving instructions to others for how to treat them, so can we please just deal with each other as individuals?

Sure, I have a do and don’t-do wishlist for my male colleages as well. Here’s my biggest wish: Unless I know you (meaning we’ve met and talked at least a few times), don’t bring me in a situation where I have to be alone with you in a closed room. Because I’ve unfortunately made some bad experiences at an early age and a situation like this sets off a major alarm in my brain. Run, it says, get out of here. I’m really sorry about this because I’m sure you’re a nice guy and play table tennis with your kids every weekend, but my neural circuits insist you’re a potential threat. That’s my biggest Don’t. But I don’t actually expect you to know this, so I’ll forgive you.

I am aware I might be stepping on some toes here, but I’m not even sure that we really need more women in physics. Because it seems to me that most women are in fact not very interested in physics, especially in theoretical physics. Of course I think it’s a shame and there are almost certainly social and cultural reasons next to genetic ones, but this doesn’t make these reasons any less real. If some girl is uncomfortable taking on a job that has a male smell to it, I think this is an important factor for their decision and for them to be happy with their life.

The social and cultural aspects can be changed, though they change only slowly, and I appreciate all efforts into this direction. Especially when it comes to children’s education and role models I believe this can serve to spark interests that otherwise might have gone unnoticed. So I certainly approve of all means to raise interest in theoretical physics, generally and specifically among young women, but I don’t see the benefit of pushing women into professions they’re not comfortable with. Gender quotas don’t make any sense to me as they seem to make the situation worse rather than better by undermining the credibility of women that benefit from it. On the shortlist for my present job there were 5 people, 3 of them women. This gives me some faith that I wasn’t hired just so there would be at least one woman in the faculty here. That did play a role in my decision to move to Sweden and so did knowing that Sweden has laws regulating a decent maternity and parental leave. (Yes, I did have another offer which was better in some sense and worse in others, so it was not a simple decision.)

I do read the studies and so I know that by all chance I’ve been subject to stereotype bias and from what I read I have to conclude that most likely I sometimes judge other women unfairly myself. This bothers me a lot. I think the best we can do is be aware of these shortcomings and try to address them systematically when we can.

But what bothers me most about the perceived male-ness of theoretical physics is that I’m afraid some women who could find much happiness with the fundamental laws of nature or the evolution of the universe never seriously consider this as a potential profession. Part of the problem is that we, myself included, rarely if ever talk about what drives us into theoretical physics and what keeps us there.

If somebody asks me what I do, I’ll tell them about black holes or gamma ray bursts or the cosmic microwave background. I don’t tell them that even after all these years what amazes me so much about theoretical physics is doing a calculation and getting a result that describes observation, something that explains the world around us. Be that the energy levels of the hydrogen atom or the double-slit experiment, Compton-scattering or gravitational lensing – these little scribbles on a notebook capture a truth about the universe. How awesome is that? And where if not theoretical physics do you find this?

I fail to see how the fascination for this connection between math and the nature of reality is a male domain, and that’s what makes me think the present low fraction of women in theoretical physics is at least partly due to misinformation about what this job is all about. But first, please, the maternity leave.

Tuesday, October 01, 2013

I'm about to fly to Vienna where I'll be attending a conference on Emergent Quantum Mechanics. I'm not entirely sure why I was invited to this event, but I suspect it's got something to do with me being one of the three people on the planet who like superdeterministic hidden variables theories, more commonly known as "conspiracy theories".

Leaving aside some loopholes that are about to be closed, tests of Bell's theorem rule out local hidden variables theories. But any theorem is only as good as the assumptions that go into it, and one of these assumptions is that the experimenter can freely chose the detector settings. As you know, I don't believe in free will, so I have an issue with this. You can see though why theories in which this assumption does not hold are known as "conspiracy theories". While they are not strictly speaking ruled out, it seems that the universe must be deliberately mean to prevent the experimentalists from doing what they want, and this option is thus often not taken seriously.

But really, this is a very misleading interpretation of superdeterminism. All that superdeterminism means is that a state cannot be prepared independently of the detector settings. That's non-local of course, but it's non-local in a soft way, in the sense that it's a correlation but doesn't necessarily imply a 'spooky' action at a distance because the backwards lightcones of the detector and state (in a reasonable universe) intersect anyway.

That having been said, you might like or not like superdeterministic hidden variables theories, the real question is if there is some way to test if that's how nature works, because one can't use Bell's theorem here. After some failed attempts, I finally came up with a possible test that is almost model-independent, and it was published in my paper "Testing super-deterministic hidden variables theories".

I actually wrote this paper in the hospital when I was pregnant. The nurses kept asking me if I'm writing a book. They were quite disappointed to be drowned in elaborations on the foundations of quantum mechanics rather than hearing a vampire story. In any case, in the expectation that the readers on this blog are somewhat more sympathetic to the question whether the universe is fundamentally deterministic or not, here a brief summary of the idea.

The central difference between standard quantum mechanics and superdeterministic hidden variables theories is that in the former case two identically prepared states can give two different measurement outcomes, while in the latter case that's not possible. Unfortunately, "identically prepared" includes the hidden variables and it's difficult to identically prepare something that you can't measure. That is after all the reason why it looks indeterministic.

However, rather than trying to prepare identical states we can try to make repeated measurements on the same state. For that, take two non-commuting variables (for example the spin or polarization in two different directions) and measure them alternately. In standard quantum mechanics the measurement outcomes will be non-correlated. In a superdeterministric hidden variables theory, they'll be correlated - provided you can make a case that the hidden variables don't change in between the measurements. The figure below shows an example for an experimental setup.

A particle (electron/photon) is bounced back and forth between
two mirrors (grey bars). The blue and red bars indicate measurements
of two non-commuting variables, only one eigenvalue passes, the
other leaves the system. The quantity to measure is the average time
it takes until the particle leaves. In a superdeterministic theory,
it can be significantly longer than in standard quantum mechanics.

The provision that the hidden variables don't change is the reason why the test is only 'almost' model independent, because I made the assumptions that the hidden variables are due to the environment (the experimental setup) down to the relevant scales of the interactions taking place. This means basically if you make the system small and cool and measure quickly enough you have a chance to see the correlation between subsequent measurements. I made some estimates (see paper) and it seems possible with today's technology to make this test.

Interestingly, after I had finished a draft of the paper, Chris Fuchs sent me a reference to a 1970 article by Eugene Wigner where, in a footnote, Wigner mentions Von Neumann discussing exactly this type of experiment:

“Von Neumann often discussed the measurement of the spin component of a spin-1/2
particle in various directions. Clearly, the possibilities
for the two possible outcomes of a single such measurement can be easily accounted for by hidden variables [...] However, Von Neumann felt
that this is not the case for many consecutive measurements of the
spin component in various different directions. The outcome of the
ﬁrst such measurement restricts the range of values which the hidden
parameters must have had before that ﬁrst measurement was undertaken. The restriction will be present also after the measurement so
that the probability distribution of the hidden variables characterizing
the spin will be different for particles for which the measurement gave
a positive result from that of the particles for which the measurement
gave a negative result. The range of the hidden variables will be further restricted in the particles for which a second measurement of the
spin component, in a different direction, also gave a positive result...”

Apparently there was a longer discussion with Schrödinger following this proposal, which could be summarized with saying that the experiment cannot test generic superdeterminism, but only certain types as I already said above. If you think about it for a moment, you can never rule out generic superdeterminism anyway, so why even bother.

I'm quite looking forward to this conference, to begin with because Vienna is a beautiful city and I haven't been there for a while, but also because I'm hoping to meet some experimentalists who can tell me if I'm nuts :p